Upon activation by antigen-presenting cells naïve T helper cells undergo clonal expansion and will ultimately differentiate in cytokine secreting effector T cells, such as Th1 and Th2 subtypes. A third and distinct effector subset has been identified, which plays a key role in providing immunity to bacteria and fungi at mucosal surfaces (Kastelein et al., Annu. Rev. Immunol. 25: 221-242, 2007). This effector T helper cell subset can be distinguished based on its ability to produce large quantities of IL-17/F, IL-21 and IL-22, and is named Th17 (Miossec et al., New Eng. J. Med. 2361: 888-898, 2009).
Different T helper subsets are characterized by the expression of lineage specific master transcription factors. Th1 and Th2 effector cells express Tbet and GATA3, respectively. A Thymocyte/T cell specific variant of Retinoic Acid Receptor-related Orphan Receptor (ROR), RORgammaT, is highly expressed in Th17 cells (He et al., Immunity 9: 797-806, 1998). RORgammaT belongs to the nuclear hormone receptor superfamily (Hirose et al., Biochem. Biophys. Res. Comm. 205: 1976-1983, 1994). RORgammaT is a truncated form of RORgamma, lacking the first N-terminal 21 amino acids and is, in contrast to RORgamma which is expressed in multiple tissues (heart, brain, kidney, lung, liver and muscle), exclusively expressed in cells of the lymphoid lineage and embryonic lymphoid tissue inducers (Sun et al., Science 288: 2369-2372, 2000; Eberl et al., Nat Immunol. 5: 64-73, 2004).
Studies using heterozygous knock-in mice replacing the RORgammaT open reading frame with GFP, revealed a constitutive expression of GFP in approximately 10% of the CD4+ T cells in the small intestinal lamina propria (LP), co-expressing the Th17 cytokines IL-17/F and IL-22 (Ivanov et al., Cell 126: 1121-1133, 2006). In mice deficient for RORgammaT, the number of Th17 cells was markedly decreased in the LP and in vitro stimulation of CD4+ T cells, under Th17 polarizing conditions resulted in a drastic decrease of IL-17 expression. These results were further substantiated via forced expression of RORgammaT in naïve CD4+ T cells, which resulted in an induction of IL-17/F and IL-22 (Ivanov et al., Cell 126: 1121-1133, 2006). Taken together demonstrating the importance of RORgammaT in differentiation and stabilization of the Th17 lineage. In addition, a ROR family member, RORalpha has been demonstrated to be involved in Th17 differentiation and stabilization (Yang et al., Immunity 28: 29-39, 2008).
Recently, RORgammaT was shown to play a crucial role in non-Th17 lymphoid cells. In these studies, RORgammaT was critically important in innate lymphoid cells expressing Thy1, SCA-1 and IL-23R proteins. Genetic disruption of RORgamma in a mouse colitis model dependent on these innate lymphoid cells, prevented colitis development (Buonocore et al., Nature 464: 1371-1375, 2010). In addition, RORgammaT was shown to play a crucial role in other non-Th17 cells, such as mast cells (Hueber et al., J. Immunol. 184: 3336-3340, 2010). Finally, RORgammaT expression and secretion of Th17-type of cytokines was reported for Lymphoid Tissue Inducer cells, NK T-cells, NK cells (Eberl et al., Nat. Immunol. 5: 64-73, 2004) and gamma-delta T-cells (Sutton et al., Nat. Immunol. 31: 331-341, 2009; Louten et al., J. Allergy Clin. Immunol. 123: 1004-1011, 2009), suggesting an important function for RORgammaT in these subtypes of cells.
Based on the role of IL-17 producing cells (either Th17 or non-Th17 cells) RORgammaT has been identified as a key mediator in the pathogenesis of several diseases (Louten et al., J. Allergy Clin. Immunol. 123: 1004-1011, 2009; Annuziato et al., Nat. Rev. Rheumatol. 5: 325-331, 2009). This was confirmed using several disease models representative of autoimmune diseases. Genetic ablation of the RORgamma gene in mice prevented the development of experimental autoimmune diseases, such as experimental autoimmune encephalomyelitis (EAE) and colitis (Ivanov et al., Cell 126:1121-33, 2006; Buonocore et al., Nature 464: 1371-1375, 2010).
Being a critical mediator in Th17-cells and other non-Th17 cells, inhibition of RORgammaT is expected to have a beneficial effect on autoimmune diseases, such as, but not limited to rheumatoid arthritis, psoriasis, multiple sclerosis, inflammatory bowel disease, Crohn's disease, and asthma (Annunziato et al., Nat. Rev. Immunol. 5: 325-331, 2009; Louten et al., J. Allergy Clin. Immunol. 123: 1004-1011, 2009). Inhibition of RORgammaT may also be beneficial in other diseases, which are characterized by increased levels of Th17 cells and/or elevated levels of Th17 hallmark cytokines such as IL-17, IL-22 and IL-23. Examples of such diseases are Kawasaki Disease (Jia et al., Clin. Exp. Immunol. 162: 131-137, 2010) and Hashimoto's thyroiditis (Figueroa-Vega et al., J. Clin. Endocrinol. Metab. 95: 953-62, 2010). Another example includes infectious diseases, such as, but not limited to, mucosal leishmaniasis (Boaventura et al., Eur. J. Immunol. 40: 2830-2836, 2010). In each of the above examples the inhibition may be enhanced by simultaneous inhibition of RORalpha.
Compounds modulating RORgammaT have been reported. Examples of agonists include T0901317 and SR1078 (Wang et al., ACS Chem. Biol. 5:1029-1034, 2010). In addition, antagonist have been reported such as 7-oxygenated sterols (Wang et al., J. Biol. Chem. 285: 5013-5025, 2009) and compounds described in EP2181710 A1.
Numerous immune and inflammatory disorders continue to afflict millions of patients worldwide. Although significant advances have been made in treating these disorders, current therapies do not provide satisfactory results for all patients due to, for example, detrimental side effects or insufficient efficacy. One exemplary immune disorder in need of better therapy is psoriasis. Various therapeutics have been developed in an attempt to treat psoriasis. However, the traditional therapies for psoriasis often have toxic adverse effects. An exemplary inflammatory disorder in need of better treatment is rheumatoid arthritis. Numerous therapeutics have been developed in an attempt to treat this disorder. However, some patients develop resistance to current therapies.
Accordingly, a need exists for improved treatments for immune disorders and inflammatory disorders. The present invention addresses this need and provides other related advantages.